Change color of each choices in a choice field dropdown

[divyavashishtha]

How can i change color of each choices in my choice field dropdown.   eg.,

Thanks in advance!

[Nirosha Uddandi]

write an onload client script on incident as 

function onLoad() {
g_form.getOption("category", "software").style.backgroundColor = "yellow";

g_form.getOption("category","inquiry").style.backgroundColor = "red";
}